Neurofibromatosis 1 (NF1) is a common autosomal dominant disorder in which affected individuals are prone to the development of both benign and malignant tumors through loss of the neurofibromin protein. Two of the most clinically challenging tumors in NF1 are the optic glioma (astrocytoma) and the malignant peripheral nerve sheath tumor (MPNST). Recent studies from our laboratories and others have shown that both NF1- associated optic glioma and MPNST exhibit high levels of mammalian target of rapamycin (mTOR) pathway activation and proliferation of Nf1-deficient cells are inhibited by agents that block mTOR activity. Our ability to more effectively treat these tumors is heavily dependent on the identification and preclinical evaluation of new chemotherapeutic compounds that target this important NF1 growth regulatory pathway. The overall objectives of this proposal are to determine how neurofibromin regulates mTOR-pathway-mediated cell growth and to identify new anti-cancer mTOR pathway inhibitory compounds suitable for the treatment of NF1- associated tumors. In this proposal, we plan to determine how neurofibromin regulates mTOR pathway activation in vitro and in vivo. Next, we propose to determine how neurofibromin-mediated mTOR pathway regulation controls cell growth. Lastly, using both a standard luciferase reporter and a recently developed novel mTOR pathway reporter, we propose to employ high-throughput chemical library screening to identify new compounds that inhibit mTOR pathway activation and the growth of Nf1-deficient cells. The availability of genetically-engineered mice and human cell lines affords us a unique opportunity for translational research in which basic science discoveries can be evaluated as potential clinical therapies. Based on the recommendations of the recent Banbury conference on "Barriers and Solutions in the Use of Mouse Models to Develop Therapeutic Strategies for Neurofibromatosis-Associated Tumors", we plan to use Nf1- deficient astrocytes and Nf1-deficient human MPNST cells as "filters" to select mTOR inhibitory agents for future trials that have the greatest likelihood of succeeding in the clinic.